RE: [RFC PATCH v1 14/14] usb:cdns3: Feature for changing role

[Pawel Laszczak]

>On 03/11/18 19:51, Pawel Laszczak wrote:
>> Patch adds feature that allow to change role from user space.
>>
>> Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
>> ---
>>  drivers/usb/cdns3/Makefile  |  2 +-
>>  drivers/usb/cdns3/core.c    |  2 +
>>  drivers/usb/cdns3/debugfs.c | 94 +++++++++++++++++++++++++++++++++++++
>>  drivers/usb/cdns3/drd.h     |  3 ++
>>  4 files changed, 100 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/usb/cdns3/debugfs.c
>>
>> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
>> index 34e60d03c4ec..08e6cdbebd46 100644
>> --- a/drivers/usb/cdns3/Makefile
>> +++ b/drivers/usb/cdns3/Makefile
>> @@ -1,7 +1,7 @@
>>  obj-$(CONFIG_USB_CDNS3)			+= cdns3.o
>>  obj-$(CONFIG_USB_CDNS3_PCI_WRAP)	+= cdns3-pci.o
>>
>> -cdns3-y					:= core.o drd.o
>> +cdns3-y					:= core.o drd.o debugfs.o
>>  cdns3-$(CONFIG_USB_CDNS3_GADGET)	+= gadget.o ep0.o debug.o
>>  cdns3-$(CONFIG_USB_CDNS3_HOST)		+= host.o
>>  cdns3-pci-y		 		:= cdns3-pci-wrap.o
>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>> index 20ae9e76940e..4012f1007da9 100644
>> --- a/drivers/usb/cdns3/core.c
>> +++ b/drivers/usb/cdns3/core.c
>> @@ -309,6 +309,7 @@ static int cdns3_probe(struct platform_device *pdev)
>>  	if (ret)
>>  		goto err4;
>>
>> +	cdns3_debugfs_init(cdns);
>>  	device_set_wakeup_capable(dev, true);
>>  	pm_runtime_set_active(dev);
>>  	pm_runtime_enable(dev);
>> @@ -346,6 +347,7 @@ static int cdns3_remove(struct platform_device *pdev)
>>  	pm_runtime_get_sync(&pdev->dev);
>>  	pm_runtime_disable(&pdev->dev);
>>  	pm_runtime_put_noidle(&pdev->dev);
>> +	cdns3_debugfs_exit(cdns);
>>  	cdns3_remove_roles(cdns);
>>  	usb_phy_shutdown(cdns->usbphy);
>>
>> diff --git a/drivers/usb/cdns3/debugfs.c b/drivers/usb/cdns3/debugfs.c
>> new file mode 100644
>> index 000000000000..d4871bc1a69d
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/debugfs.c
>> @@ -0,0 +1,94 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Cadence USBSS DRD Controller DebugFS filer.
>> + *
>> + * Copyright (C) 2018 Cadence.
>> + *
>> + * Author: Pawel Laszczak <pawell@xxxxxxxxxxx>
>> + */
>> +
>> +#include <linux/types.h>
>> +#include <linux/debugfs.h>
>> +#include <linux/seq_file.h>
>> +#include <linux/uaccess.h>
>> +
>> +#include "core.h"
>> +#include "gadget.h"
>> +
>> +static int cdns3_mode_show(struct seq_file *s, void *unused)
>> +{
>> +	struct cdns3		*cdns = s->private;
>> +
>> +	switch (cdns->role) {
>> +	case CDNS3_ROLE_HOST:
>> +		seq_puts(s, "host\n");
>> +		break;
>> +	case CDNS3_ROLE_GADGET:
>> +		seq_puts(s, "device\n");
>> +		break;
>> +	case CDNS3_ROLE_OTG:
>> +	case CDNS3_ROLE_END:
>> +		seq_puts(s, "otg\n");
>> +		break;
>> +	default:
>> +		seq_puts(s, "UNKNOWN mode\n");
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int cdns3_mode_open(struct inode *inode, struct file *file)
>> +{
>> +	return single_open(file, cdns3_mode_show, inode->i_private);
>> +}
>> +
>> +static ssize_t cdns3_mode_write(struct file *file,
>> +				const char __user *ubuf,
>> +				size_t count, loff_t *ppos)
>> +{
>> +	struct seq_file		*s = file->private_data;
>> +	struct cdns3		*cdns = s->private;
>> +	u32			mode = 0;
>> +	char			buf[32];
>> +
>> +	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
>> +		return -EFAULT;
>> +
>> +	if (!strncmp(buf, "host", 4))
>> +		mode = USB_DR_MODE_HOST;
>> +
>> +	if (!strncmp(buf, "device", 6))
>> +		mode = USB_DR_MODE_PERIPHERAL;
>> +
>> +	if (!strncmp(buf, "otg", 3))
>> +		mode = USB_DR_MODE_OTG;
>> +
>> +	cdns->desired_role = mode;
>> +	queue_work(system_freezable_wq, &cdns->role_switch_wq);
>
>If we start with OTG mode and user says change mode to device will we still
>switch to host based on ID pin change?
>
>If it does then this isn't working correctly.
>We need to stop processing ID interrupts and keep the role static till
>the user switches it back to otg.

Switching role form user space will limited driver only to selected mode. 
Only for USB_DR_MODE_OTG driver should base on ID pin. 
That's my intension.

>> +	return count;
>> +}
>> +
>> +static const struct file_operations cdns3_mode_fops = {
>> +	.open			= cdns3_mode_open,
>> +	.write			= cdns3_mode_write,
>> +	.read			= seq_read,
>> +	.llseek			= seq_lseek,
>> +	.release		= single_release,
>> +};
>> +
>> +void cdns3_debugfs_init(struct cdns3 *cdns)
>> +{
>> +	struct dentry *root;
>> +
>> +	root = debugfs_create_dir(dev_name(cdns->dev), NULL);
>> +	cdns->root = root;
>> +	if (IS_ENABLED(CONFIG_USB_CDNS3_GADGET) &&
>> +	    IS_ENABLED(CONFIG_USB_CDNS3_HOST))
>> +		debugfs_create_file("mode", 0644, root, cdns,
>> +				    &cdns3_mode_fops);
>> +}
>> +
>> +void cdns3_debugfs_exit(struct cdns3 *cdns)
>> +{
>> +	debugfs_remove_recursive(cdns->root);
>> +}
>> diff --git a/drivers/usb/cdns3/drd.h b/drivers/usb/cdns3/drd.h
>> index 85731f3b693c..5344290c76f2 100644
>> --- a/drivers/usb/cdns3/drd.h
>> +++ b/drivers/usb/cdns3/drd.h
>> @@ -119,4 +119,7 @@ int cdns3_drd_probe(struct cdns3 *cdns);
>>  void cdns3_set_hw_mode(struct cdns3 *cdns, u32 mode);
>>  irqreturn_t cdns3_drd_irq(struct cdns3 *cdns);
>>
>> +void cdns3_debugfs_init(struct cdns3 *cdns);
>> +void cdns3_debugfs_exit(struct cdns3 *cdns);
>> +
>>  #endif /* __LINUX_CDNS3_DRD */
>>
>
>cheers,
>-roger
>--
>Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
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Thanks,
Cheers,
Pawel